The present invention relates to a fluid flow regulating apparatus for a fluid mechanism and in particular to an exhaust flow speed regulating apparatus for a handheld pneumatic power tool.
In assembly and manufacturing processes involving power tools, speed control has become a desired feature due to the increased use of composite and laminate materials in end product designs. These materials are much more sensitive to tool speeds due to burning and chipping that can occur during machining processes. Moreover, the higher expectation of tolerance control during machining does not permit over-powering powering a power tool through such materials. These problems encountered although prevalent in generally all machining processes are particularly exacerbated during high-speed operations such as drilling.
Thus, it is desirable to obtain different motor speeds for a power tool using the same motor construction. Typically this can be done by sizing and shaping an orifice in the fluid flow path to restrict fluid flow to a predetermined mass rate of flow, thus limiting motor speed. Such speed regulation is typically accomplished by regulating air on the inlet side of the motor using a variable regulating valve or, alternatively, with many single use permanent parts. However, the disadvantages of the known speed regulating devices are that regulating valves are complex and subject to wear and partial operation. Permanent parts reduce the flexibility of converting the tool and create logistical problems in manufacturing the various parts. Both alternatives are costly to construct. Moreover, when reducing the speed of a tool by regulating the inlet air to the tool, the stall torque and horsepower of the motor are significantly lowered.
The foregoing illustrates limitations known to exist in present pneumatic operated power tools. Thus it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly a suitable alternative is provided including the features more fully disclosed hereinafter.
According to the present invention, a speed regulating apparatus for a pneumatic tool is provided having a housing with at least one exhaust opening and a speed regulating apparatus. The speed regulating apparatus has a cap that is removably mounted on the housing and has at least one exhaust port in fluid communication with the at least one exhaust opening. A control ring is provided having at least one aperture in fluid communication with and rotatably mounted over the at least one exhaust port, with the control ring being movable to variably open and close the at least one exhaust port.
The foregoing and other aspects of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. It must be understood, however, that the figures are not intended as definitions of the invention but are only for the purpose of illustration.